TECHNOLOGY OF MANUFACTURE OF RADIO ABSORPTION CERAMICS

The object of the work is the technology of manufacturing radio-absorbing ceramics on the basis of facing tiles with the addition of silicon carbide. The method of hydrostatic weighing in water was used to determine the physical properties. X-ray phase analysis and spectral characteristics - transmission and reflection coefficients, in the frequency range 25.8 – 37.5 GHz were also determined. Tiles consist of two layers. First, separately obtain a press powder for the I and II layer of raw materials in a given amount, which were weighed, moistened, ground in a ball mill; the slip was dried in an oven, then ground and passed through a suitable sieve. The moistened press powder for the first layer was weighed and poured into a mold for pressing, after which the moistened press powder for the second layer was weighed and poured into the mold for pressing. The resulting raw material was dried. The semi-finished product was covered with watering and placed in an oven. The finished semi-finished product was fired in a silite furnace. The two-layer tile with an irrigated covering made on the developed technology was characterized by the following characteristics: water absorption – 9,8 %, imaginary density – 1,90 g/cm3. The developed ceramics, according to the classification, can be referred to the class of radio-absorbing ceramics.

Influence of the firing temperature on the dielectric properties of ceramics based on barium titanate

The object of the research is the firing temperature of ceramic materials based on barium titanate. In laboratory conditions, barium titanate was synthesized from raw materials of barium carbonate and titanium dioxide using ceramic technology, taking into account the stoichiometric composition of the compound. In order to study the effect of the firing temperature on the properties of the ceramic material, three temperatures were selected: 1270, 1300, and 1350 °C. The physical properties of the samples (imaginary density, water absorption, open porosity) were determined by the method of hydrostatic weighing in water. The samples were saturated with water after their preliminary evacuation. The dielectric characteristics of the obtained materials were measured on an E7-8CLR automated device (Ukraine) at a frequency of 1 kHz. The structural and morphological features of ceramics based on synthesized barium titanate were investigated by direct scanning electron microscopy and X-ray phase analysis. On the basis of the complex of studies carried out, the technological parameters of the production of ceramics were selected. Thus, the duration of grinding at the first and second stages is 10 and 30 minutes; moisture content of the press powder – 8 %; pressing pressure – 20 MPa; temperature of the first firing – 1000 °С; temperature of the second firing – 1350 °C. The regularity of the change in the dielectric constant on the firing temperature of ceramics based on barium titanate was established. The investigated samples, obtained according to the given technological regime, are characterized by the following indicators: dielectric constant – 259.9; open porosity – 0.02 %; water absorption – 0.01 %; imaginary density – 5.45 g/cm3. The resulting material can be used to create composite ceramic materials that protect biological and technical objects from the effects of electromagnetic radiation, and can also be used to create new functional materials for space, aerospace, electronic engineering and medicine.

The Press Powder Technological Parameters Optimization in Wall Ceramics Production by the Semi-Dry Pressing Method

The paper presents the fundamental possibility of using ash and slag waste (ASW) of the fuel and energy complex in the production of ceramic bricks using the semi-dry pressing method based on the Buguruslan deposit low-melting aluminosilicate loams. The technological parameters optimization ways (molding moisture, grinding fineness, pressing pressure) in the production of ceramic bricks from low-quality clay raw materials using the experiment mathematical planning method are presented. The separate and joint grinding raw materials mixture rational composition influence on the ceramics technological properties is studied.

Obtaining a Hard Alloy Powder from a Worn-Out Tools with a Subsequent Use for Pressing Rods

The article presents the results of research on obtaining powder of hard alloy using various methods. The analysis of studies described in the literature. Currently, there are many ways to obtain powders from waste, but most of them are poorly applicable in practice in a particular plant. On the basis of the data obtained from the literature, a method of obtaining powder was selected, which can be used in an enterprise with the equipment available. Technological regimes were also selected, which included such operations as softening the workpieces, mechanical grinding, grinding the powder in a ball mill, making press powder, molding, sintering, and tool making processes. The resulting blanks were further compared with a standard tool for cutting edge resistance and the presence of external and internal defects. The work carried out has shown the possibility of using technological regimes for the production of powders on existing equipment for the subsequent manufacture of cutting tools. This technology allows to reduce costs and product cost without significant loss in product quality, which makes it possible to compete with other manufacturers of carbide tools. In the future, it is planned to develop and optimize the existing technology to improve product quality. The paper presents the results of research of obtaining a hard alloy powder with a different methods. Comparison of products from different powders and the subsequent pressing rods, their sintering and examination of defects

Influence of Morphology of the Press Powder Particles and Thermal Annealing on the Structure and Microhardness of Palladium Obtained by Solid-Phase Sintering

The article is devoted to the investigation of the structure of pressed palladium-barium cathodes. These cathodes are made from a polycrystalline palladium matrix with inclusions of the particles of the activator phase Pd5Ba. The high efficiency and durability of pressed palladium-barium cathodes is ensured by the formation of an active-emission BaO layer on the working surface. The active metal Ba comes from the volume to the surface by diffusion of atoms on the defects of the crystal structure of the palladium matrix. When comparing the electrical parameters of the cathodes, the matrices of which were made from the same fractions but different batches of palladium powder, a considerable spread of electrical parameters was established. There were also revealed significant differences in the roughness of the cathode working surface. These differences affect the uniformity and stability of the emission current. This indicates the need for a detailed study of the characteristics of the initial palladium powder and their effect on the structure of the sintered material, and, consequently, on the physicomechanical properties of its surface. In this paper, the morphological features of eight batches of palladium powder in the initial state and after the purification annealing were studied by the method of electron microscopy. Significant differences in the form of particles and agglomerates of powder from different batches have been revealed. A metallographic analysis of microsections of the palladium samples prepared by solid-phase sintering was carried out. The influence of the morphological features of the particles of the initial powder on the grain size and the mechanical properties of the sintered compact is determined. Studies have shown that to obtain a compact palladium with reproducible and predictable properties, stability of the morphological characteristics of the original powder is necessary.

LLC «Rzhevkirpich» impact on the environment and environmental management of the territory

A sharp increase of anthropogenic impact on the environment has created a real threat to the ecological crisis. A huge variety of natural resources use in human activities led to the use of a systematic approach to the environmental management analysis, as well as to environmental management. This paper considers Rzhev brick factory impact on such environmental components as air, hydrosphere, soil and lithosphere. Currently, the production of bricks is one of the leading sectors of the building materials industry, accounting for more than 50% of the total production of wall materials. From the environmental point of pollution occurs at all stages of production: raw materials preparation (crushing, grinding, sifting, etc.), mixing of starting components into a homogeneous good shape commodity (preparation of press-powder with the use of emaciated and burnable additives, hydration, heating and mixing) and production with the help of various methods of pressing. As a result of the analysis the authors suggest a complex of measures to minimize negative impacts on the environment and health of workers and the public. As brick plants are widely distributed on the territory of the Russian Federation and as they are quite often located in urban areas, the market for brick production develops, the authors think that the subject is very relevant and important from a practical point of view.

The Influence of Molding Powder Breakup on the Sintered Ceramic Quality

This paper assesses the moldability of press-powder with different fractional composition. Different types of defects that occur in ceramic materials due to insufficient or overpressure of molding of press powderare analyzed. Based on results of structural studies and evaluation of the physical properties of materials recommendations on the molding selection modes of press-powders with different fractional composition that provide the absence of defects in the compacts and obtaining quality dense ceramics are formulated.

A new Li-Mn-Ge-O phase solved by combining 3D electron diffraction methods

Pyroxene compounds are a common form of natural minerals and have been studied as such for a long time. More recently the research on quasi-one-dimensional magnetic and multiferroïc materials has renewed the interest in pyroxenes of the stoichiometry AMX2O6 (A = alkali metal, M = transition metal, X = Si or Ge), since the magnetic M3+ ions form chains. Chemical substitution on the A and M sites can change the magnetic coupling along these chains making this system a rich field for the exploration of new phases of interesting magnetic properties [1]. In this work we report the discovery of a new phase in the Li-Mn-Ge-O system. A HP-HT solid state reaction was performed on a mixture of nominal stoichiometry LiMnGe2O6 during 1 h at a temperature of 8500C and a pressure of 3 GPa in a belt press. Powder X-ray diffraction yielded a diffractogram that could not be indexed by known phases of this system. An electron diffraction study in a transmission electron microscope was conducted in order to identify any unknown phases. In the case of structures that promise interesting properties a more targeted synthesis can then be undertaken. For the purpose of this work, we studied one of several unknown phases in the powder in more detail. From standard selected area electron diffraction the unit cell was determined to be triclinic with cell parameters a = 2.51 nm, b = 1.30 nm, c = 1.30 nm, α = 96.00, β = 98.80and γ = 80.80. No comparable unit cell could be found in the databases neither in this system nor with different A, M or X ions. Intensities were recorded by in-zone axis precession electron diffraction and by electron diffraction tomography. Combining the data from both methods yielded the first model of the structure which we will present here.